Shadow's Return
by Umbram Consolationis
Summary: For over a decade Finn has been known only as the hero of Ooo, but Hunson's amulet awakens something within Finn, and old memories and powers now flood back over him. This is not Finn's only concern however, as deep within the bowels of the Nightosphere something ancient and terrible begins to stir, and if it is not stopped, all of Ooo will feel its wrath.
1. Chapter 1

Finn lay on the floor of his home breathing deep, ragged breaths. There was joy and elation at saving Marcy from her father, but it was washed away by something far larger and more powerful.  
He gritted his teeth as the pain hit him. The searing, lightning pain of thoughts and memories beyond count, once lost, now returning to him in a flood that tore at the halls of his mind.  
He remembered a name his name.  
He remembered...

_**Obscurus!**_

Peppermint Butler looked at himself in the mirror as he put on his tie. _A party to celebrate a momentous occasion!_ he thought. Indeed, what Finn had done in the Nightosphere was no small achievement, but this was not what made Peppermint Butler smile.  
What made him smile was the thought of just how far Finn had come, and how this all began over a decade ago at the summit of a ruined keep.

Peppermint stood in the rain, staring at his opponent. His opponent, a foul and ancient vampire lord, stared back in mild amusement.  
"Tell me, little breath mint. Why have you come to me this oh so damp evening?" he asked, smirking at Peppermint.  
"To destroy you, monster of the night!" he shouted back defiantly.  
The vampire only laughed. "Pray, tell me how, oh courageous fool," he spat.  
"With this!" Peppermint yelled as he drew out the rune and began to cast the spell.

The vampire shrieked as it hit him. "What vile, contemptible mage-craft is this, that you send flying my way?" he shouted in anger.  
"A spell gifted to me by the demons of the Nightosphere, that will strip you of all your strength, thus allowing me to end you, monster," Peppermint smirked.  
The vampire fell to his knees as he weakened, blue lightning encasing his body. At last he looked up at Peppermint and shouted, "This will not end me! We will meet again, Breath mint!" Then, in a flash of blinding light, he was gone, and in his place lay something Peppermint did not expect. A helpless babe with a glowing symbol on his chest. The symbol matched the rune the demons had given him. As Peppermint lifted the child up the rune faded and was gone. Now he would, as the demons promised him, be able to destroy him forever with ease, and yet, he could not. There was no part of him capable of killing this child.

So instead he allowed it to live, and watched as it grew, with no memory of its former self into the greatest hero he and Ooo had ever seen.  
Peppermint smiled. He was proud of how well this had turned out.  
He walked out into the main hall where the party was in full swing. He was about to go greet the late guests when he was caught on the arm by one of the servants.  
"Milord," he whispered, "Lord Finn wishes to speak with you on the balcony." Peppermint was surprised at this. Finn neither cared for titles, nor did he usually request to speak to him. Of course this night was for Finn so he would indulge him.  
He stepped out onto the balcony and saw Finn looking off into the stars. He was not in his usual attire, instead he wore a pair of black dress pants and a black button-up shirt, with a pair of well-polished leather shoes.  
"The party inside is for you, sir, surely you wish to enjoy it to the fullest?" he asked politely.  
Finn gave a small laugh. "You may dispense with the niceties little one," he said.  
Peppermint wondered at this remark, when Finn turned, revealing the top buttons of his shirt to be undone.  
Peppermint's eyes widened in horror. There, on his chest, was the rune, glowing like fire.  
It's nice to see you again, Breath mint...

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Author's note: I apologise for the short chapter, and I hope to make them longer in future. As per the norm I own nothing but the concept behind my sort-of OC and AU. Everything else belongs to Pendleton Ward. All constructive criticism is welcome.


	2. Chapter 2

Peppermint Butler's eyes widened in horror.

He raised his hands to cast a spell, but Finn was faster, and blasted him against the wall with a bolt of crimson lightning. Peppermint looked up, dazed and in pain. Finn was advancing upon him with slow, deliberate steps. "If you're going to kill me, make it quick!", Pepper snarled.

"Kill you?", Finn gave a small laugh," I'm not going to kill you, not yet at least." He stooped down and, grabbing Pepper by the throat, lifted him off the ground and pinned him against the wall.

"Why is that?" Pepper choked out as Finn's hand tightened around his throat.

"Two reasons. First: you are too useful at this current time," Finn released his grip, and pepper fell to the floor gasping for air. "Second,"Finn continued," I can't."

"What?" Pepper looked up at him in bewilderment. "What do you mean you can't?"

"It seems I have overestimated your intelligence," Finn snarled. "What I mean, is that I am physically incapable of killing you. You see, your ward, though rapidly weakening, is still in effect, thus severely limiting my power, making me unable to kill you with magic." Finn sat on the edge of the balcony railing and drew a small dagger from a sheath on his ankle. "At least I have other means besides magic." At this he gave a small smile and at that moment Pepper saw Obscurus shine through the boyish exterior. It unsettled him.

"So now what?" asked Pepper edging his way towards the exit into the main hall._ If I could just reach it! _he thought.

Before he could get any closer Finn was between him and it."Now comes the real surprise!"

Pepper tensed and waited for the blow...and waited...and waited. He opened his eyes to a sight that left him dumbfounded. Finn, the monster Obscurus, was kneeling before him with his head bowed.

"Wha...What are you doing?" Pepper asked wearily surveying the situation for possible traps. Finn looked up, a pair of crimson reptilian eyes meeting Pepper's gaze.

In a voice saturated by his true age and power, he began,"Peppermint Butler, servant of her majesty Princess Bubblegum, noble ruler of the Candy Kingdom, I pledge to you and to all innocent and pure folk of Ooo my protection and strength to the day that I may meet my final demise."

Pepper stood, stunned before the bowing figure. "Why?" was the only word he could muster.

"You judged me poorly Breath Mint." Finn stood and dusted off his knees. "I was not the monster you took me for, but a paladin for the weak, sworn to protect them from those who sought dominion over them. It was simply a necessity that I evetually became one such monster."

"If that is true it would mean that I condemned an innocent man to over a decade of punishment." Pepper said, suddenly feeling somewhat foolish.

"Punishment?" Obscurus burst into a fit of laughter. "This was no punishment. I have made many fond memories in my time as Finn: the hero of Ooo!" he swept his arms out in a grand gesture to emphasise the weight of his title.

His face suddenly twisted into a grimace.

"What is wrong?" Pepper asked, concerned as to the truthfulness of these claims.

"I have just realized something," Obscurus said, his brow furrowing.

"Which is?"

"My brother, Jake, is not so fond of vampires, and when he realizes that his brother is about to become a very old, very powerful one..." he trailed off into silence, and began pacing.

"You realize he is not actually your brother, do you not?"

Obscurus spun round, his eyes ablaze," Any man who fights at my side on the battlefield, whose blood mixes with mine on the broken ground, whose sword defends my life has earned the right to be called my brother! Jake has earned that and so much more." he shouted.

Peppermint backed away slightly from the enraged vampire. "I see," Peppermint gave a small sigh,"If he has truly earned so much then there is but one thing to do." He walked to the door. Just before he walked through, he turned his head to the figure behind him and said," You must tell him." He walked into the main hall and was gone.

Obscurus looked up into the star-filled night and sighed. Annoyingly, the glorified after-dinner treat was right.

This was going to be problematic...


	3. Chapter 3

Obscurus walked nonchalantly through the crowds at the party, considering the possible implications of revealing his identity to Jake. On one hand he may accept it and learn to live with it and perhaps may become an invaluable asset. On the other he may also freak out and go completely spare, and probably try and kill him with a wooden stake or some other cliched method. Obscurus gave a snort of derision at the idea that he could be slain by something used to keep tents in place.

He was pulled from his thoughts by a sharp pain splitting his head. He doubled over as his nose was assaulted by a barrage of smells and he was nearly deafened by a wall of noise coming from the crowds. He looked up in search of the source of the sensations, and was startled by what he saw.

He could see each guest's circulatory systems. He watched as the multitude of hearts pumped liters of blood to its various destinations. His stomach gave a slight growl. Another massive ache in his head ended his hunger and brought a fresh wave of panic. He thought frantically to try and deduce what was wrong.

He calmed as realisation dawned upon him. The ward was weakening faster than he had originally thought. His senses had already returned to their original strength, and he was simply overloaded by the shear amount of information.

He straightened as he acclimatised to the new power of his perception. He turned at a shrill call from across the hall. It was Princess Bubblegum, rapidly making her way towards him. This was by far and away the last thing he needed at that current moment. Yet, it was his duty as her "paladin" to at least inquire as to what she desired of him.

As she approached something about her heart caught his attention. As he expected it was made of candy, but there was something odd about it. It was a three-chambered heart. _Like an amphibian's _he thought. The similarity between her and a toad made him snigger slightly.

" And what is so funny oh brave hero?" she inquired. "Nothing! Nothing at all," he said, quite glad when she seemed to accept the answer. "I have a request Finn," she began. _Of course you do. Why else would you be talking to the likes of me? _he thought fighting back a snarl. "You see," she continued," I need some help with one of my experiments, nothing drastic of course, just some minor gene manipulation."

Obscurus gave a slight grin," I would love to Princess, but unfortunately I have some rather pressing business to attend to, so I'm afraid I cannot aid you in your infantile machinations today my dear." He turned and walked off before she could answer doing his best nobleman stride, a trick he had perfected almost two millennia ago.

As he neared the door out of the hall, he saw Marceline floating lazily over the crowd. Obscurus couldn't help but stare. She had forgone her usual punk rocker attire for a long flowing black dress. The floating only made it that much more hypnotic as the dress swayed and billowed as she moved. Upon spotting him she descended and came to a stop just above his head grinning down at him. " Hi hero!" She cocked her head slightly in confusion. "Where's that goofy hat of yours?" she inquired. "I thought I'd give it a rest for the night," he ran his fingers over the buttons on his shirt to ensure that the ward was covered. " Do you like the new look?" he gave a slight twirl to show off his new choice of clothing. She grinned," Love it!"

After bidding the vampiric beauty farewell he walked out of the door and into the night air. He breathed in the scents of a sleeping city and looked up into the stars. He hadn't regained enough power to fully shape shift, but he could at least do so this. He closed his eyes in concentration, and a pair of massive feathered, black wings sprouted from his back. He grinned in pure ecstasy as he took off and felt the wind rush through his hair.


	4. Chapter 4

Authors note: I would just like to thank everyone who favourited and reviewed the story. It is an amazing confidence boost! Anyway on with the chapter.

* * *

This was not going according to plan...

The gumdrop monk scrabbled desperately to pick up the book, which he knew to be his only protection against the monster he had summoned...or at least tried to. What had actually happened when he completed the incantation was that he was teleported instantaneously to IT.

At last he managed to grab hold of the rough leather cover of the ancient tome. Breathing a sigh of relief he finally looked up and took in his surroundings. He immediately regretted this decision. To say he was in a room would have been a wild guess. All that could be seen outside of the glow from his tiny, solitary candle was a void of pure black. The kind of black that made the eyes water and numbed the mind.

He blinked and tried to concentrate on the tome. _What was it called again?_ he thought desperately. _Grim-something...grimace? Grimer? No...something odd...with a strange pronunciation. Grimoas? YES! That was it._ He gave a small fist-pump in victory. This joy was to be short-lived however.

He was torn from his celebration by a voice in the darkness. "WHO DARES ENTER MY REALM?", came the challenge like a thunderclap. The gumdrop looked up, swallowed, then shouted back defiantly,"I am Mark the Young of the Gumdrop Monk Order, and I am here to bind you in the service of my great leader, Princess Bubblegum!" His bravado died somewhat when the only answer was a laugh.

"You will not mock me monster!" , he shouted indignantly and with that he opened the book and began to read the passage which he had been told would bind the demon. What had escaped him up to this point was that he had no idea how to read the language the book was written in, and furthermore reading a magical rite with no knowledge of its meaning was as effective as lighting an oil lamp filled with soil. It was an unfortunate fact that the demon knew this, and thus saw an opportunity.

The monk finished the rite and looked up triumphantly,"What do you say now, demon?" "ASK OF ME, MASTER, AND I SHALL DO,"answered the darkness, trying to keep amusement out of its booming voice. The monk swelled with pride and then made a statement which was equivalent to an axe to his own throat, born of his new-found pride, and the greed born of possessing power. "You will grant me the following: wisdom, freedom from the brotherhood and an unending existence!"

The demon laughed,"SO BE IT. I GIVE YOU THE WISDOM OF KNOWING NEVER TO CROSS A DEMON, I GRANT YOU FREEDOM FROM YOUR PATHETIC BROTHERHOOD AS YOU SHALL NEVER RETURN TO THEM AGAIN AND FINALLY I GRANT YOU AN EXISTENCE IN THE UNENDING STATE OF DEATH!" The darkness lunged.

The monks last moments were spent screaming as the demon tore the flesh from his body and ate the life-force that flowed from it.

An hour or so later the demon had finished its task, and clothed in its new suit of living flesh crafted from the life-force of the monk, looked to the door of its prison. "HEAR ME PEOPLE OF THE LIVING WORLD!"

"ABANDON YOUR POSTS!"

"ABANDON YOUR HOMES!"

"ABANDON ALL HOPE!"

Wind rustled the branches of the tree-house. A spider sunk its fangs into a fly with a "thunk!". An acorn fell and bounced off the ground.

Obscurus inclined his head to a new sound, his eyes shut to aid in re-honing his senses. This sound was much closer. Crackling of fat and oil mingling with thawing ice in the bottom of a pan, and underneath it the soft hiss of a gas next thing to reach him was the smell. The pungent and alluring stench of cooking meat, specifically bacon.

He opened his eyes. Jake was standing at the stove preparing his breakfast, a copious amount of bacon. Obscurus got up from the couch he was sitting on and stalked silently towards his adoptive brother. When he stood but a meter from Jake he said, admittedly louder than he needed to,"Smells good."

He watched in slight amusement as his friend went stiff as a board, before slowly turning around, trying to hide his fright and failing rather miserably."Don't do that to me man!" Jake snapped before dropping the spatula he had been using on the bacon.

"Do what?" Obscurus asked, putting on his best innocent face, rather an achievement for a vampire.

"Sneaking up on me." Jake responded, returning to the task at hand.

Obscurus gave a mock gasp,"Me sneak up on the great hound who, only a week ago had declared he could hear the sound of an ant's fart five miles away?"

Jake responded by ignoring him and aggressively flipping the bacon. Too aggressively, it proved, as he splashed hot oil over his foot. With a yelp he fell to the floor clutching his wounded appendage. This spectacle was too much for Obscurus who began laughing, which only served to annoy Jake further.

Jake started up with a scolding, but soon stopped when he remembered who he was addressing, then he went back to the bacon grumbling.

Obscurus walked back to the couch and sat down again to watch his brother prepare a bacon sandwich with extra bacon and a side of bacon. He was actually quite surprised at how quickly his friend had adjusted to the knowledge of his past. He had, mostly, accepted it and moved on. "Mostly", as Jake now slept every night wearing a chain mail scarf despite the fact that it was the height of summer and all of the reassurance Obscurus had given him regarding his feeding habits.

Speaking of feeding, Obscurus was planning the hunt which he would undertake that night. He would prowl the outskirts of the Candy Kingdom, looking for bandits, deer or anything else that would provide a satisfactory amount of blood to sate his rapidly growing thirst.

Therein lay the problem with vampirism. The more powerful the vampire the more fuel the power needed and the more that power deformed the vampire when revealed.

Deformed...

Obscurus looked down at his hands. The skin had very pale and was almost ghostly white, while his nails had turned black, and had begun to taper at the ends, forming blunt precursors to the vicious claws they would eventually become. His canines had also sharpened and his eyes were now permanently bloodshot, which would eventually turn into the dull red glow of vampiric eyes. His hair too had begun to grow darker. This all pointed to one conclusion.

He would eventually have to reveal himself, and that would unlock a whole new Pandora's Box of troubles.

He was pulled from his thoughts by a knock at the door.


	5. Chapter 5

When a monster appears everybody scatters, running like headless chickens all over the country-side, searching desperately for a hero, begging him or her for their protection. What few realise is that this is a futile effort.

Monsters do not fear heroes. If an amoured knight storms a wyvern, shouting at the top of his lungs he will almost certainly end up in its digestive tract in the near future. If a priest attacks a vampire with a cross, the vampire will drain him dry. If a hunter goes after a werewolf armed to the teeth with silver and wolfsbane, he will be hanging, decapitated from a tree branch within minutes.

No, when you need to combat monsters you do not look for hereos. You look for bigger, scarier monsters.

_It must be an intimidating sight_ Obscurus thought, as they crashed through one of the many lines of shrubbery that criss-crossed the planes. He was referring to the sight that would have greeted any spectators to his journey. That sight being a heavily-armed adolescent astride a massive salivating dog, which was sprinting at full speed across the grassy planes that bordered the outskirts of the Candy Kingdom.

Their destination was a small village nestled at the foot of the mountains that marked the beginning of the Ice King's domain.

They had sent a call for aid via a courier. The message, though obviously scrawled in a paniced hurry, was still very clear. It consisted of only two words:"DRAGON ATTACK".

The village came into sight, above it a huge colloumn of black smoke rose into the sky.

Obscurus was not worried. He had faced the dragons of Ooo many times. They were true products of the mutagenic cloud released by the Lich's bomb. They were poorly-proportioned creatures, with massive elongated bodies and a pair of pitiful little wings barely able to keep the beasts aloft. The only threat they really posed was that of fire, as they could breathe a form of gas-powered flame which could set thatch roofing ablaze with ease.

Jake halted as a shadow passed over them. Obscurus looked up to assess the size of their opponent and was struck by what he saw. It was by no means one of the dragons of Ooo. The creature attacking this town was a Great Drake, a species that, to the best of his knowledge, had lain dormant underground for nearly two thousand years.

A Great Drake was a far more formiddable opponent. A long spiked tail, two massive wings, four legs each with feat whose toes were tipped with claws as long as a toddler was high and a large, horned head which spewed a burning, napalm-like substance capable of melting steel.

To make matters worse, this one seemed entirely set on reducing the village to a smoldering ruin.

Obscurus nudged Jake's flank with his foot, urging him to keep moving. Jake remained motionless.

Obscurus gave him a slightly harder nudge.

Still nothing.

Jake was completely transfixed by the terrifying beauty of the creature circling above, and it was only when Obscurus gave him a sharp kick in the ribs that he finally broke from his trance.

"Ow! What was that for?", he brought one massive paw up to rub his injured ribs, destablising Obscurus in the process, who, far to gracefully for Jake's liking, slid off the other side to land on his feet.

Obscurus turned to his companion. "If you are quite done ogling our opponent, we still have a job to do!" With that he set off toward the burning village.

Jake shrunk to his original size and hurried after Obscurus. "I wasn't ogling it! It's just...it...it's really big." He looked up again wearily. The dragon had disappeared into the smoke, which unsettled Jake slightly.

"I've seen you get bigger than that."

"Yeah...but I can't breathe fire."

The village itself was deserted, all of the inhabitants having long ago evacuated. This combined with the dragon's sudden departure and the dying of the flames created an earie silence.

Obscurus turned to his adoptive brother. "Jake, check the buildings for anything unusual. Dragons like that one don't attack without reason. The villagers had to have done something to aggrivate it."

"What am I looking for?"

"Anything that looks out of place: a pile of gold, a jewel that looks like it came from a dragon-horde or maybe a large glowing egg, anything."

Jake set off, nose to the ground, in search of whatever it was that the dragon was looking for.

Obscurus found an upturned market cart and leaned against it, pondering the dragon's retreat. He knew that Great Drakes were highly-sensitive to magic as all creatures of the ancient world were, but his power was far too weakened at the moment to be seen as a threat and Jake's abillities were not inherintaly offensive, thus it could not have been them that frightened it away.

As he stood there he heard it, not with his ears but with his mind, with his soul. It was a long, low rumble. It grew and grew till it shook the very foundations of his spirit.

_No wonder the dragon left_ Obscurus thought to himself. _Few creatures are able to face down the power of a Demonic Ancient._

Author's note: Sorry for not updating sooner, things were a bit hectic, but I hope to make updates more regular in future. Also I would just like to thank everyone who reviewed for the positive feedback and criticism, it has been a great help and an amazing confidence boost!


	6. Chapter 6

Obscurus walked through the ruins of the town, following the rythmic vibrations which beat against the very fibres of his being. Apprehension gnawed at him as he crossed a rubble-strewn street and entered a narrow alley.

One of the buildings which made up the walls of the alley had been knocked loose from its foundation and had begun to lean slightly dropping masonry and thatch all over the alley. As he walked below it his muscles tensed as his ears picked up the sound of cracking mortar.

He dove to the left just in time to avoid being hit by a massive, four-poster bed, which had broken through the wall of the crumbling structure. It shattered upon impact sending splinters and feathers into the air.

After picking himself up off the floor Obscurus gave a disgruntled sneeze and continued down the alley.

Upon exiting the alley he was greeted by a sight which left him less than amused. The building which contained the source of the rumbling, in accordance to all laws governing bad luck and obeying the command of whatever vindictive bastard controlled his own horrific fortunes, was a church.

Now it was not true that vampires burst into flames upon touching holy ground, but it did leave them disoriented. The effect would be lessened by his current state but would still be well within the range of noticibility.

He walked up to the threshold and stood staring at the small cobbled path which led to the church door. He braced himself. Took a step...and nothing.

He opened his eyes. He took another step. Still nothing.

He knew that if Christianity had managed to survive the mushroom war then the rites to sanctify ground had too, which meant only one alternative. Whatever was in that church was so powerful that it had managed to corrupt holy ground.

"Shit."


	7. Chapter 7

Obscurus stepped into the church building and surveyed his surroundings. In stark contrast to the rest of the village it was almost untouched, the only evidence of any untoward events being a few small fragments of the wood supports lying on the ground.

He became acutely aware of the silence within the church. It was unnatural, as if something were actively muting all sound from the outside, leaving only a dull absence which strained the ears. To anyone else it would have been unnerving, however it only served to intrigue Obscurus.

He made his way through dust-covered rows of seats. The silence seemed to grow more intense the closer he came to the pulpit. He scaled the short stairs up to the lectern and leaned over it to peer at the other he then saw actually did unnerv him.

It was the body of the priest, recently dead judging by the state of his clothes. The corpse however was dessicated and shrivelled, as if the life had been sucked from it violently. The face was set with the jaws wide open. The poor creature had been screaming as it died.

A red glow caught Obscurus's attention.

Clutched in the priest's hand was a small gem, emitting a crimson light from its core. With a great deal of apprehension Obscurus reached out and grasped the gem. When nothing happened, he wrenched it free. The hand crumbled to dust as he did so.

He gazed at the gem. It seemed to have been expertly cut, the light gleaming from each angle and the crimson glow pulsed like a heartbeat. He ran his finger over it. The surface was so unnaturally smooth that instead of being beautiful it seemed eerie, as if it did not belong anywhere near the natural world.

He was pulled from his thoughts by Jake calling to him from outside.

He turned to the corpse and tore a shred from the cloth of its robe, before wrapping it around the gem and placing it gently within his backpack.

He spun on his heels and returned the way he had come. When he exited the door he took in a deep breath. Even though the act was rapidly becoming unnecessary it still comforted him to take in the scents of the wind. Even the smoke was better than the smell of stale and fettid air that seemed to permiate the church building.

After rejoining Jake they walked out of the village together, chatting idly about what they should do to prevent the dragon from returning to the area.

Moments after their departure the church collapsed.

Two figures clad in deep black robes stood on a hillside overlooking the ruined village. One turned to the other,"So...he has returned."

"Is returning," the other corrected him.

"I doubt correct verb tense is the greatest of our concerns here, Sir." He shifted anxiously from foot to foot. "We should inform Gabriel."

"No."

The response seemed to strike the first speaker dumb for a few moments. He quickly recovered and, undaunted, tried again,"But if that thing has returned it may threaten the balance, and besides Gabriel gave us specific orders that should Obscurus ever reappear..."

He was cut off by the firm hand on his shoulder."Our orders on this matter come from above Gabriel."

The first speaker fell silent, now feeling somewhat foolish before his older counterpart.

"And another thing young one", his companion continued in a voice like glacial ice,"that 'thing' as you so eloquently put it, was once one of our brothers and is a far more skilled warrior than you or I, making a direct confrontation with him undesirable." He now seemed to soften slightly and continued jovially,"Besides, I am hungry and in need of rest. I hear their is a town with a good inn only a few miles from here!"

With a grin he set off down the hill, humming a tune to himself. His companion lingered a few moments longer, before joining him, jogging slightly to catch up.

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**Author's note: I just want to apologise for the long absence but I'm happy to announce that I will be increasing my post rate from now on! Also a new chapter to my other fanfic will be coming out soon. Thank you to all of you for your patience and I hope you enjoyed the chapter, as more is coming soon!**


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